title: Design and expression of a dimeric form of human immunodeficiency virus type 1 antibody 2G12 with increased neutralization potency.
abstract: The antigen-binding fragment of the broadly neutralizing human immunodeficiency virus type 1 (HIV-1) antibody 2G12 has an unusual three-dimensional (3D) domain-swapped structure with two aligned combining sites that facilitates recognition of its carbohydrate epitope on gp120. When expressed as an intact immunoglobulin G (IgG), 2G12 formed typical IgG monomers containing two combining sites and a small fraction of a higher-molecular-weight species, which showed a significant increase in neutralization potency (50- to 80-fold compared to 2G12 monomer) across a range of clade A and B strains of HIV-1. Here we show that the higher-molecular-weight species corresponds to a 2G12 dimer containing four combining sites and present a model for how intermolecular 3D domain swapping could create a 2G12 dimer. Based on the structural model for a 3D domain-swapped 2G12 dimer, we designed and tested a series of 2G12 mutants predicted to increase the ratio of 2G12 dimer to monomer. We report a mutation that effectively increases the 2G12 dimer/monomer ratio without decreasing the expression yield. Increasing the proportion of 2G12 dimer compared to monomer could lead to a more potent reagent for gene therapy or passive immunization.
authors.affiliation: Division of Biology, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA.
authors.forename: Anthony P
authors.initials: AP
authors.lastname: West
authors.forename: Rachel P
authors.initials: RP
authors.lastname: Galimidi
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Foglesong
authors.forename: Priyanthi N P
authors.initials: PN
authors.lastname: Gnanapragasam
authors.forename: Kathryn E
authors.initials: KE
authors.lastname: Huey-Tubman
authors.forename: Joshua S
authors.initials: JS
authors.lastname: Klein
authors.forename: Maria D
authors.initials: MD
authors.lastname: Suzuki
authors.forename: Noreen E
authors.initials: NE
authors.lastname: Tiangco
authors.forename: Jost
authors.initials: J
authors.lastname: Vielmetter
authors.forename: Pamela J
authors.initials: PJ
authors.lastname: Bjorkman
mesh_terms: D019943:Amino Acid Substitution; D000911:Antibodies, Monoclonal / Q000235:genetics* / Q000276:immunology*; D019281:Dimerization; D015483:HIV Antibodies / Q000235:genetics* / Q000276:immunology*; D015497:HIV-1 / Q000276:immunology*; D006801:Humans; D020128:Inhibitory Concentration 50; D008958:Models, Molecular; D020125:Mutation, Missense; D009500:Neutralization Tests; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D020349:Surface Plasmon Resonance
chemical_list: D000911:Antibodies, Monoclonal; D015483:HIV Antibodies